The present invention relates to a process for the carbonylation of arylalkyl halides to form an arylalkylpyruvic acid as the predominant product. More particularly, the present invention relates to the carbonylation of an arylalkyl halide to form benzylpyruvic acid and other arylalkylpyruvic acids containing in the aromatic part of their molecules a benzene ring which may or may not be substituted or condensed benzene rings which also may or may not be substituted.
The practical value of such .alpha.-keto-carboxylic acids and their salts is that they play an important role in biochemistry. For example, they have been found to be useful as hypoglycemics.
It is known in the art to prepare arylpyruvic acids. Specifically pertinent to the process of the present invention is U.S. Pat. No. 4,152,352 which discloses the preparation of an arylpyruvic acid by reacting an arylmethyl halide in a liquid solvent medium with carbon monoxide at pressures of 5 to 200 bars in the presence of a catalytic amount of a metal carbonyl compound and an alkaline earth metal inorganic base. Also pertinent is U.K. patent application No. 2,026,478A, which discloses that alkali metal salts of an arylpyruvic acid can be prepared by reacting an arylmethyl halide, carbon monoxide and an alkali metal base in the presence of a metal carbonyl compound as catalyst and in the presence of an alcohol or cyclic ether as solvent.
While the art demonstrates that arylpyruvic acids can be made by reacting an arylmethyl halide with carbon monoxide in the presence of a carbonyl compound and a basic substance, it would be unexpected that less reactive arylalkyl halides having more than one methylene group attached to the aromatic moiety in their structure could be carbonylated under similar reaction conditions to form arylalkylpyruvic acids.